Re: [PATCH v6 5/8] iio: adc: fsl,imx25-gcq driver

[Jonathan Cameron <jic23@kernel.org>]

On 29/01/15 14:09, Markus Pargmann wrote:
> This is a conversion queue driver for the mx25 SoC. It uses the central
> ADC which is used by two seperate independent queues. This driver
> prepares different conversion configurations for each possible input.
> For a conversion it creates a conversionqueue of one item with the
> correct configuration for the chosen channel. It then executes the queue
> once and disables the conversion queue afterwards.
> 
> The reference voltages are configurable through devicetree subnodes,
> depending on the connections of the ADC inputs.
> 
> Signed-off-by: Markus Pargmann <mpa@pengutronix.de>
> Signed-off-by: Denis Carikli <denis@eukrea.com>
> Signed-off-by: Markus Pargmann <mpa@pengutronix.de>
Some really small bits and bobs inline...
Only non trivial one is that I'd prefer that the need for a regulator
in the event of an external reference being specified was explicitly enforced.
> ---
>  drivers/iio/adc/Kconfig                     |   7 +
>  drivers/iio/adc/Makefile                    |   1 +
>  drivers/iio/adc/fsl-imx25-gcq.c             | 361 ++++++++++++++++++++++++++++
>  include/dt-bindings/iio/adc/fsl-imx25-gcq.h |  18 ++
>  4 files changed, 387 insertions(+)
>  create mode 100644 drivers/iio/adc/fsl-imx25-gcq.c
>  create mode 100644 include/dt-bindings/iio/adc/fsl-imx25-gcq.h
> 
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index 0f79e4725763..fccbb4bf44cc 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -143,6 +143,13 @@ config EXYNOS_ADC
>  	  of SoCs for drivers such as the touchscreen and hwmon to use to share
>  	  this resource.
>  
> +config FSL_MX25_ADC
> +	tristate "Freescale MX25 ADC driver"
> +	depends on MFD_MX25_TSADC
> +	help
> +	  Generic Conversion Queue driver used for general purpose ADC in the
> +	  MX25. This driver supports single measurements using the MX25 ADC.
> +
>  config LP8788_ADC
>  	tristate "LP8788 ADC driver"
>  	depends on MFD_LP8788
> diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
> index 701fdb7c96aa..acab8d956371 100644
> --- a/drivers/iio/adc/Makefile
> +++ b/drivers/iio/adc/Makefile
> @@ -16,6 +16,7 @@ obj-$(CONFIG_AD799X) += ad799x.o
>  obj-$(CONFIG_AT91_ADC) += at91_adc.o
>  obj-$(CONFIG_AXP288_ADC) += axp288_adc.o
>  obj-$(CONFIG_EXYNOS_ADC) += exynos_adc.o
> +obj-$(CONFIG_FSL_MX25_ADC) += fsl-imx25-gcq.o
>  obj-$(CONFIG_LP8788_ADC) += lp8788_adc.o
>  obj-$(CONFIG_MAX1027) += max1027.o
>  obj-$(CONFIG_MAX1363) += max1363.o
> diff --git a/drivers/iio/adc/fsl-imx25-gcq.c b/drivers/iio/adc/fsl-imx25-gcq.c
> new file mode 100644
> index 000000000000..398e40c0e4fd
> --- /dev/null
> +++ b/drivers/iio/adc/fsl-imx25-gcq.c
> @@ -0,0 +1,361 @@
> +/*
> + * Copyright 2014 Markus Pargmann, Pengutronix <mpa@pengutronix.de>
> + *
> + * The code contained herein is licensed under the GNU General Public
> + * License. You may obtain a copy of the GNU General Public License
> + * Version 2 or later at the following locations:
> + *
> + * http://www.opensource.org/licenses/gpl-license.html
> + * http://www.gnu.org/copyleft/gpl.html
> + *
> + * This is the driver for the imx25 GCQ (Generic Conversion Queue)
> + * connected to the imx25 ADC.
> + */
> +
> +#include <dt-bindings/iio/adc/fsl-imx25-gcq.h>
> +#include <linux/clk.h>
> +#include <linux/iio/iio.h>
> +#include <linux/interrupt.h>
> +#include <linux/mfd/imx25-tsadc.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +#include <linux/regulator/consumer.h>
> +
> +#define MX25_GCQ_TIMEOUT (msecs_to_jiffies(2000))
> +
> +enum mx25_gcq_cfgs {
> +	MX25_CFG_XP = 0,
> +	MX25_CFG_YP,
> +	MX25_CFG_XN,
> +	MX25_CFG_YN,
> +	MX25_CFG_WIPER,
> +	MX25_CFG_INAUX0,
> +	MX25_CFG_INAUX1,
> +	MX25_CFG_INAUX2,
> +	MX25_NUM_CFGS,
> +};
> +
> +struct mx25_gcq_priv {
> +	struct regmap *regs;
> +	struct completion completed;
> +	unsigned int settling_time;
> +	struct clk *clk;
> +	int irq;
> +	struct regulator *ext_vref;
> +	u32 channel_vref_mv[MX25_NUM_CFGS];
> +};
> +
> +#define MX25_CQG_CHAN(chan, id) {\
> +	.type = IIO_VOLTAGE,\
> +	.indexed = 1,\
> +	.channel = chan,\
> +	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),\
> +	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),\
> +	.datasheet_name = id,\
> +}
> +
> +static const struct iio_chan_spec mx25_gcq_channels[MX25_NUM_CFGS] = {
> +	MX25_CQG_CHAN(0, "xp"),
> +	MX25_CQG_CHAN(1, "yp"),
> +	MX25_CQG_CHAN(2, "xn"),
> +	MX25_CQG_CHAN(3, "yn"),
> +	MX25_CQG_CHAN(4, "wiper"),
> +	MX25_CQG_CHAN(5, "inaux0"),
> +	MX25_CQG_CHAN(6, "inaux1"),
> +	MX25_CQG_CHAN(7, "inaux2"),
> +};
> +
I'd be tempted to not bother separating out the next two given they
are only used in one place each..
> +static void mx25_gcq_disable_eoq(struct mx25_gcq_priv *priv)
> +{
> +	regmap_update_bits(priv->regs, MX25_ADCQ_MR, MX25_ADCQ_MR_EOQ_IRQ,
> +			   MX25_ADCQ_MR_EOQ_IRQ);
> +}
> +
> +static void mx25_gcq_enable_eoq(struct mx25_gcq_priv *priv)
> +{
> +	regmap_update_bits(priv->regs, MX25_ADCQ_MR,
> +			   MX25_ADCQ_MR_EOQ_IRQ, 0);
> +}
> +
> +static irqreturn_t mx25_gcq_irq(int irq, void *data)
> +{
> +	struct mx25_gcq_priv *priv = data;
> +	u32 stats;
> +
> +	regmap_read(priv->regs, MX25_ADCQ_SR, &stats);
> +
> +	if (stats & MX25_ADCQ_SR_EOQ) {
> +		mx25_gcq_disable_eoq(priv);
> +		complete(&priv->completed);
> +	}
> +
> +	/* Disable conversion queue run */
> +	regmap_update_bits(priv->regs, MX25_ADCQ_CR, MX25_ADCQ_CR_FQS, 0);
> +
> +	/* Acknowledge all possible irqs */
> +	regmap_write(priv->regs, MX25_ADCQ_SR, MX25_ADCQ_SR_FRR |
> +		     MX25_ADCQ_SR_FUR | MX25_ADCQ_SR_FOR |
> +		     MX25_ADCQ_SR_EOQ | MX25_ADCQ_SR_PD);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static int mx25_gcq_get_raw_value(struct device *dev,
> +				  struct iio_chan_spec const *chan,
> +				  struct mx25_gcq_priv *priv,
> +				  int *val)
> +{
> +	long timeout;
> +	u32 data;
> +
> +	/* Setup the configuration we want to use */
> +	regmap_write(priv->regs, MX25_ADCQ_ITEM_7_0,
> +		     MX25_ADCQ_ITEM(0, chan->channel));
> +
> +	mx25_gcq_enable_eoq(priv);
> +
> +	/* Trigger queue for one run */
> +	regmap_update_bits(priv->regs, MX25_ADCQ_CR, MX25_ADCQ_CR_FQS,
> +			   MX25_ADCQ_CR_FQS);
> +
> +	timeout = wait_for_completion_interruptible_timeout(
> +		&priv->completed, MX25_GCQ_TIMEOUT);
> +	if (timeout < 0) {
> +		dev_err(dev,
> +			"ADC wait for measurement failed\n");
> +		return timeout;
> +	} else if (timeout == 0) {
> +		dev_err(dev, "ADC timed out\n");
> +		return -ETIMEDOUT;
> +	}
> +
> +	regmap_read(priv->regs, MX25_ADCQ_FIFO, &data);
> +
> +	*val = MX25_ADCQ_FIFO_DATA(data);
> +
> +	return IIO_VAL_INT;
> +}
> +
> +static int mx25_gcq_read_raw(struct iio_dev *indio_dev,
> +			     struct iio_chan_spec const *chan, int *val,
> +			     int *val2, long mask)
> +{
> +	struct mx25_gcq_priv *priv = iio_priv(indio_dev);
> +	int ret = 0;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		mutex_lock(&indio_dev->mlock);
> +		ret = mx25_gcq_get_raw_value(&indio_dev->dev, chan, priv, val);
> +		mutex_unlock(&indio_dev->mlock);
> +		return ret;
> +
> +	case IIO_CHAN_INFO_SCALE:
> +		*val = priv->channel_vref_mv[chan->channel];
> +		*val2 = 12;
> +		return IIO_VAL_FRACTIONAL_LOG2;
> +
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static const struct iio_info mx25_gcq_iio_info = {
> +	.read_raw = mx25_gcq_read_raw,
> +};
> +
> +static const struct regmap_config mx25_gcq_regconfig = {
> +	.max_register = 0x5c,
> +	.reg_bits = 32,
> +	.val_bits = 32,
> +	.reg_stride = 4,
> +};
> +
> +static int mx25_gcq_setup_cfgs(struct platform_device *pdev,
> +			       struct mx25_gcq_priv *priv)
> +{
> +	struct device_node *np = pdev->dev.of_node;
> +	struct device_node *child;
> +	struct device *dev = &pdev->dev;
> +	int ret, i;
> +
> +	/*
> +	 * Setup all configurations registers with a default conversion
> +	 * configuration for each input
> +	 */
> +	for (i = 0; i < MX25_NUM_CFGS; ++i)
> +		regmap_write(priv->regs, MX25_ADCQ_CFG(i),
> +			     MX25_ADCQ_CFG_YPLL_OFF |
> +			     MX25_ADCQ_CFG_XNUR_OFF |
> +			     MX25_ADCQ_CFG_XPUL_OFF |
> +			     MX25_ADCQ_CFG_REFP_INT |
> +			     MX25_ADCQ_CFG_IN(i) |
> +			     MX25_ADCQ_CFG_REFN_NGND2);
> +
> +	for_each_child_of_node(np, child) {
> +		u32 reg;
> +		u32 refp = MX25_ADCQ_CFG_REFP_INT;
> +		u32 refn = MX25_ADCQ_CFG_REFN_NGND2;
> +
> +		ret = of_property_read_u32(child, "reg", &reg);
> +		if (ret) {
> +			dev_err(dev, "Failed to get reg property\n");
> +			return ret;
> +		}
> +
> +		if (reg >= MX25_NUM_CFGS) {
> +			dev_err(dev,
> +				"reg value is greater than the number of available configuration registers\n");
> +			return -EINVAL;
> +		}
> +
> +		of_property_read_u32(child, "fsl,adc-refp", &refp);
> +		of_property_read_u32(child, "fsl,adc-refn", &refn);
> +
> +		/*
> +		 * Shift the read values to the correct positions within the
> +		 * register.
> +		 */
> +		refp = MX25_ADCQ_CFG_REFP(refp);
> +		refn = MX25_ADCQ_CFG_REFN(refn);
> +
> +		if ((refp & MX25_ADCQ_CFG_REFP_MASK) != refp) {
> +			dev_err(dev, "Invalid fsl,adc-refp property value\n");
> +			return -EINVAL;
> +		}
> +		if ((refn & MX25_ADCQ_CFG_REFN_MASK) != refn) {
> +			dev_err(dev, "Invalid fsl,adc-refn property value");
> +			return -EINVAL;
> +		}
> +
> +		regmap_update_bits(priv->regs, MX25_ADCQ_CFG(reg),
> +				   MX25_ADCQ_CFG_REFP_MASK |
> +				   MX25_ADCQ_CFG_REFN_MASK,
> +				   refp | refn);
> +	}
> +	regmap_update_bits(priv->regs, MX25_ADCQ_CR,
> +			   MX25_ADCQ_CR_FRST | MX25_ADCQ_CR_QRST,
> +			   MX25_ADCQ_CR_FRST | MX25_ADCQ_CR_QRST);
> +
> +	regmap_write(priv->regs, MX25_ADCQ_CR,
> +		     MX25_ADCQ_CR_PDMSK |
> +		     MX25_ADCQ_CR_QSM_FQS);
Odd line breaking. I certainly wouldn't break the last two lines.
> +
> +	return 0;
> +}
> +
> +static int mx25_gcq_probe(struct platform_device *pdev)
> +{
> +	struct iio_dev *indio_dev;
> +	struct mx25_gcq_priv *priv;
> +	struct mx25_tsadc *tsadc = dev_get_drvdata(pdev->dev.parent);
> +	struct device *dev = &pdev->dev;
> +	struct resource *res;
> +	void __iomem *mem;
> +	int ret;
> +
> +	indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*priv));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	priv = iio_priv(indio_dev);
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	mem = devm_ioremap_resource(dev, res);
> +	if (!mem)
> +		return -ENOMEM;
> +
> +	priv->regs = devm_regmap_init_mmio(dev, mem, &mx25_gcq_regconfig);
> +	if (IS_ERR(priv->regs)) {
> +		dev_err(dev, "Failed to initialize regmap\n");
> +		return PTR_ERR(priv->regs);
> +	}
> +
> +	init_completion(&priv->completed);
> +
> +	/* Optional external regulator */
> +	priv->ext_vref = devm_regulator_get(&pdev->dev, "vref");
> +	if (!IS_ERR_OR_NULL(priv->ext_vref)) {
> +		ret = regulator_enable(priv->ext_vref);
This is documented in the bindings as being only optional in the sense
that there may or may not be channels using it.  I'd be inclined
to have it as non optional, but only request it if in use.

If truely optional then should be using the get_optional form as otherwise
IIRC the regulator framework will feed you a dummy regulator under some
circumstances.
> +		if (ret)
> +			return ret;
> +	}
> +
> +	ret = mx25_gcq_setup_cfgs(pdev, priv);
> +	if (ret)
> +		return ret;
> +
> +	priv->clk = tsadc->clk;
> +	ret = clk_prepare_enable(priv->clk);
> +	if (ret) {
> +		dev_err(dev, "Failed to enable clock\n");
> +		return ret;
> +	}
> +
> +	priv->irq = platform_get_irq(pdev, 0);
> +	if (priv->irq <= 0) {
> +		dev_err(dev, "Failed to get IRQ\n");
> +		ret = priv->irq;
> +		goto err_clk_unprepare;
> +	}
> +
> +	ret = request_irq(priv->irq, mx25_gcq_irq, 0, pdev->name, priv);
> +	if (ret) {
> +		dev_err(dev, "Failed requesting IRQ\n");
> +		goto err_clk_unprepare;
> +	}
> +
> +	indio_dev->dev.parent = &pdev->dev;
> +	indio_dev->channels = mx25_gcq_channels;
> +	indio_dev->num_channels = ARRAY_SIZE(mx25_gcq_channels);
> +	indio_dev->info = &mx25_gcq_iio_info;
> +
> +	ret = iio_device_register(indio_dev);
> +	if (ret) {
> +		dev_err(dev, "Failed to register iio device\n");
> +		goto err_irq_free;
> +	}
> +
> +	platform_set_drvdata(pdev, priv);
I'd normally prefer slightly if this used the indio_dev
(just a case of logically what contains what...)
Doesn't really matter though.
> +
> +	return 0;
> +
> +err_irq_free:
> +	free_irq(priv->irq, (void *)priv);
> +err_clk_unprepare:
> +	clk_disable_unprepare(priv->clk);
> +	return ret;
> +}
> +
> +static int mx25_gcq_remove(struct platform_device *pdev)
> +{
> +	struct mx25_gcq_priv *priv = platform_get_drvdata(pdev);
> +	struct iio_dev *indio_dev = iio_priv_to_dev(pdev);
> +
> +	iio_device_unregister(indio_dev);
> +	free_irq(priv->irq, priv);
> +	clk_disable_unprepare(priv->clk);
> +
> +	return 0;
> +}
> +
> +static struct of_device_id mx25_gcq_ids[] = {
> +	{ .compatible = "fsl,imx25-gcq", },
> +	{ /* Sentinel */ }
> +};
> +
> +static struct platform_driver mx25_gcq_driver = {
> +	.driver		= {
> +		.name	= "mx25-gcq",
> +		.of_match_table = mx25_gcq_ids,
> +	},
> +	.probe		= mx25_gcq_probe,
> +	.remove		= mx25_gcq_remove,
> +};
> +module_platform_driver(mx25_gcq_driver);
> +
> +MODULE_DESCRIPTION("ADC driver for Freescale mx25");
> +MODULE_AUTHOR("Markus Pargmann <mpa@pengutronix.de>");
> +MODULE_LICENSE("GPL v2");
> diff --git a/include/dt-bindings/iio/adc/fsl-imx25-gcq.h b/include/dt-bindings/iio/adc/fsl-imx25-gcq.h
> new file mode 100644
> index 000000000000..4f2f4a9baafe
> --- /dev/null
> +++ b/include/dt-bindings/iio/adc/fsl-imx25-gcq.h
> @@ -0,0 +1,18 @@
> +/*
> + * This header provides constants for configuring the I.MX25 ADC
> + */
> +
> +#ifndef _DT_BINDINGS_IIO_ADC_FS_IMX25_GCQ_H
> +#define _DT_BINDINGS_IIO_ADC_FS_IMX25_GCQ_H
> +
> +#define MX25_ADC_REFP_YP	0 /* YP voltage reference */
> +#define MX25_ADC_REFP_XP	1 /* XP voltage reference */
> +#define MX25_ADC_REFP_INT	2 /* Internal voltage reference */
> +#define MX25_ADC_REFP_EXT	3 /* External voltage reference */
> +
> +#define MX25_ADC_REFN_XN	0
> +#define MX25_ADC_REFN_YN	1
> +#define MX25_ADC_REFN_NGND	2
> +#define MX25_ADC_REFN_NGND2	3
> +
> +#endif
>